a,(-x+y)-(x-y )²
b, (3x+4y) – (2x ² +2x +1)
c, – ( 4x+1) – (-6x+2 )
d, (x ² + 4) ² + (x-y) (x+y)
e (x-y+z).(x-y-z)
g ( x ²+ 2x + 1) . (x ² + 1)
a,(-x+y)-(x-y )² b, (3x+4y) – (2x ² +2x +1) c, – ( 4x+1) – (-6x+2 ) d, (x ² + 4) ² + (x-y) (x+y) e (x-y+z).(x-y-z) g ( x ²+ 2x + 1) . (x ² + 1)
By Anna
`#DyHungg`
`a) (-x+y)-(x-y)²`
`=-x-y-x²+2xy-y^2`
…………
`b) (3x+4y)-(2x²+2x+1)`
`=3x+4y-2x²-2x-1`
`=x+4y-2x²-1`
`c) -(4x+1)-(-6x+2)`
`=-4x-1+6x-2`
`=2x-3`
`d) (x²+4)²+(x-y)(x+y)`
`=x^4+8x²+16+x²-y²`
`=x^4+9x^2+16-y^2`
`e) (x-y+z)(x-y-z)`
`=(x-y)²-z²`
`=x²-2xy+y²-x²`
`g) (x²+2x+1)(x²+1)`
`=x^4+2x³+2x²+2x+1`
Đáp án:
$\begin{array}{l}
a)\left( { – x + y} \right) – {\left( {x – y} \right)^2}\\
= – x + y – \left( {{x^2} – 2xy + {y^2}} \right)\\
= – x + y – {x^2} + 2xy + {y^2}\\
b)\left( {3x + 4y} \right) – \left( {2{x^2} + 2x + 1} \right)\\
= 3x + 4y – 2{x^2} – 2x – 1\\
= – 2{x^2} + x + 4y – 1\\
c) – \left( {4x + 1} \right) – \left( { – 6x + 2} \right)\\
= – 4x – 1 + 6x – 2\\
= 2x – 3\\
d){\left( {{x^2} + 4} \right)^2} + \left( {x – y} \right)\left( {x + y} \right)\\
= {x^4} + 8{x^2} + 16 + {x^2} – {y^2}\\
= {x^4} + 9{x^2} + 16 – {y^2}\\
e)\left( {x – y + z} \right)\left( {x – y – z} \right)\\
= {\left( {x – y} \right)^2} – {z^2}\\
= {x^2} – 2xy + {y^2} – {z^2}\\
g)\left( {{x^2} + 2x + 1} \right)\left( {{x^2} + 1} \right)\\
= {x^4} + {x^2} + 2{x^3} + 2x + {x^2} + 1\\
= {x^4} + 2{x^3} + 2{x^2} + 2x + 1
\end{array}$